Effect Of A Branched-chain Amino Acids Supplementation On Muscle Soreness During Intensive Training Program

PURPOSE It is well known that branched-chain amino acids (BCAA) are essential amino acids that can be oxidized in skeletal muscle, and the oxidation is promoted by exercise. Some research suggest that BCAA intake increases muscle protein synthesis after exercise. Thus, we investigated the effect of a BCAA supplement on muscle soreness, and the activities of serum enzymes during a 5-day intensive endurance training program. METHODS Sixteen male distance runners, age (20.2 +/− 1.8 years), height (171 +/− 4 cm) and weight (57.3 +/− 4.4 kg) were divided into two groups and subjected to a double-blind examination. One group received an oral BCAA supplement for 5 days (5g leucine, 2.5g isoleucine and 2.5g valine per day, 450kcal), while another group received a placebo (non-BCAA, 450kcal). During these 5 days, all subjects completed the supplement and training program, consisting of 3 timed training sessions (total 40 km) per day. Muscle soreness over the whole body (SOR-WB) and in the pressed ankle extensor muscles (SOR-AE) were evaluated by a visual analog scale (a 10-cm line, 0: no pain, 10: extremely painful) every morning. Blood samples taken at rest before and after the training period were analyzed for activities of serum creatine kinase, lactate dehydrogenase and aldorase as indicators of muscle damage. RESULTS Significant low values of soreness were found in BCAA (1.8 +/− 1.9 cm in SOR-WB and 3.3 +/− 1.9 score in SOR-AE) than those in placebo (3.9 +/− 2.0 cm in SOR-WB and 6.2 +/− 2.6 score in SOR-AE). However, these perceived changes could not be directly attributed to the differences in activities of serum creatine kinase (111.1 +/− 140.5 in BCAA and 181.4 +/− 147.0 in placebo, IU/L), lactate dehydrogenase (53.9 +/− 60.6 in BCAA and 67.7 +/− 27.7 in placebo, IU/L) and aldorase (2.1 +/− 1.5 in BCAA and 2.4 +/− 1.5 in placebo, IU/L). CONCLUSIONS We concluded that BCAA supplementation during an intensive training program was effective to attenuate perceived muscle soreness, and that the basic mechanism underling the effect remains unknown.